🐛 BUG: pyodide needs updating to support to_py for JS -> python conversion

[thecapacity]

Which Cloudflare product(s) does this pertain to?

Workers Runtime

What versions are you using?

wrangler 3.99.0

What operating system and version are you using?

Mac Sonoma 14.6.1

Please provide a link to a minimal reproduction

No response

Describe the Bug

This is all from an environment I built fresh on Jan 1 2025 - e.g. brew install node etc.

It appears pyodide is an alpha version:
pyodide Version: 0.26.0a2

print( f"{dir(pyodide)}") results in:

['ConversionError', 'IN_BROWSER', 'InternalError', 'JsArray', 'JsAsyncGenerator', 'JsAsyncIterable', 'JsAsyncIterator', 'JsBuffer', 'JsCallable', 'JsDomElement', 'JsDoubleProxy', 'JsException', 'JsFetchResponse', 'JsGenerator', 'JsIterable', 'JsIterator', 'JsMap', 'JsMutableMap', 'JsPromise', 'JsProxy', 'JsTypedArray', 'all', 'builtins', 'cached', 'doc', 'file', 'loader', 'name', 'package', 'path', 'spec', '_pyodide', '_pyodide_core', 'create_once_callable', 'create_proxy', 'destroy_proxies', 'register_js_module', 'sys', 't', 'to_js', 'unregister_js_module']

More specifically I'm looking for the to_py(...) function, so I can convert the data = await request.json() object from Javascript to Python. Supposedly, per ChatGPT, this function was introduced in pyodide version 0.21.0. But regardless it's in the latest version on their site.

https://pyodide.org/en/stable/usage/api/python-api/ffi.html#pyodide.ffi.JsArray.to_py

Please provide any relevant error logs

Error: PythonError: Traceback (most recent call last):
File "/lib/python312.zip/_pyodide/_base.py", line 629, in pyimport_impl
res = import(stem, fromlist=fromlist)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/session/metadata/entry.py", line 9, in
from pyodide.ffi import to_py
ImportError: cannot import name 'to_py' from 'pyodide.ffi' (/lib/python312.zip/pyodide/ffi/init.py)

at async Object.fetch (file:///Users/.../node_modules/miniflare/dist/src/workers/core/entry.worker.js:1029:22)

[thecapacity]

I still think this is a valid bug but I think I found the way to do this:

        elif request.method == "POST":
            data = await request.json()
            data = data.to_py()

[thecapacity]

Sorry meant to comment not close w/ comment

[dom96]

I've definitely used to_py with the version of Pyodide that is currently shipped in Python Workers. Can you share a more complete example of your worker code?

[hoodmane]

to_py is a method on jsproxy objects, to_js is a function. I think everything is working as intended.